This adds support for custom properties on the remainder of the
CSSStyleDeclaration methods.
A shorthand that was specified using a variable reference is serialized
to its originally specified value, rather than by concatenating the
serializations of its longhand components.
A shorthand that was not specified using a variable references but which
has a component longhand that was is serialized to the empty string.
This adds a CSSVariableDeclarations object to nsRuleData and adds a
MapRuleInfoInto function to CSSVariableDeclarations so the can copy
variable declarations into a nsRuleData's object. We call that from
Declaration::Map{Normal,Important}RuleInfoInto.
We make HasImportantData return true if we have important variables
but no important non-custom properties on a declaration, since that
is used to determine whether we have a rule node for important
declarations. This means MapImportantRuleInfoInto can no longer
assume that mImportantData is non-null.
Patch co-authored by Emmanuele Bassi <ebassi@gmail.com>
This defines a CSSVariableDeclarations class that holds a set of
variable declarations. This is at the specified value stage, so values
can either be 'initial', 'inherit' or a token stream (which is what you
normally have). The variables are stored in a hash table. Although
it's a bit of a hack, we store 'initial' and 'inherit' using special
string values that can't be valid token streams (we use "!" and ";").
Declaration objects now can have two CSSVariableDeclarations objects
on them, to store normal and !important variable declarations. So that
we keep preserving the order of declarations on the object, we inflate
mOrder to store uint32_ts, where values from eCSSProperty_COUNT onwards
represent custom properties. mVariableOrder stores the names of the
variables corresponding to those entries in mOrder.
We also add a new nsCSSProperty value, eCSSPropertyExtra_variable, which
is used to represent any custom property name.
nsCSSProps::LookupProperty can return this value.
The changes to nsCSSParser are straightforward. Custom properties
are parsed and checked for syntactic validity (e.g. "var(a,)" being
invalid) and stored on the Declaration. We use nsCSSScanner's
recording ability to grab the unparsed CSS string corresponding to
the variable's value.
This inverts the relationship between segments and properties in the
animation data structures: now each property has a set of segments,
since the segments differ between properties.
Furthermore, we now handle inability to interpolate between values by
dropping the entire property rather than dropping a single segment.
